Access to water of good quality is of vital concern for mankind globally. Especially on the emerging markets the challenge is very real with many water stressed countries. The availability of clean and safe water is a major problem in both developed and developing countries. At present the world is facing difficult challenge in meeting the increasing demand of potable water systems due to population growth, urbanization, increasing pollution of water bodies from various industrial and agricultural activities, heavy rain, and drought caused by climate change and demands from various users (Vörösmarty et al, 2000; Lee et al. 2005; Moe et al, 2006; Coetser et al, 2007, Theron et al 2008). According to the WHO, more than 1 billion people, mostly in the developing countries, still do not have access to an adequate supply of drinking water (World Health Organization 2004) and as a result, the quality of health and welfare of vulnerable groups (children, the elderly and poor) are dependent on the availability of safe and affordable water supply (Theron et al, 2008; Theron et al, 2002).
The fact remains, though, that a growing human population demands clean and safe drinking water from the community. It is estimated that 2.2 billion people lack access to clean and safe water. There are 900 million water related sicknesses per year half of the world's hospital beds are filled with people suffering from water related diseases (World Health Organization), mostly affecting children and women. Every year two million children die or one every 15 seconds as a result of drinking contaminated water (World Health Organization). These are incredible numbers.
Municipal wastewater treatment plants which take care of household wastewater as well as industrial effluent are the main source of contamination to rivers and lakes. Treated and untreated water as well as overflows go directly to the nature and may pose a threat to water ecosystems in lakes and rivers. Water from lakes and rivers moreover is the source of drinking water.
Despite the fact that drinking water is our most common and valuable commodity there is a lack of practical real time monitoring and detection systems as well as proper treatment systems which address the need of detecting possible micro contaminants such as bacteria and parasites and pharmaceutical residues in drinking water. Improved surveillance and sampling systems together with effective treatment are needed to detect and avoid any sudden deterioration in water quality and to actuate proper measures, like effective disinfection or polishing.
There are several on line instruments available in the market today, e.g instruments for measuring TOC (total organic carbon), BOD (biological oxygen demand), ions, chlorine, DO (dissolved oxygen) and so on. The most common, though, in all the water treatment plants worldwide is to measure pH, temperature, turbidity and chlorine. These parameters are not processed and do not give any information about microbiological growth nor danger for parasites like Cryptosporidium and Giardia nor increased organic matter and so on.
Two important examples of pathogenic microorganisms that may be transmitted to humans by contaminated water are Giardia and Cryptosporidium. Cryptosporidium oocysts are common and widespread in ambient water and can persist for months in this environment. The dose necessary to infect humans (i.e. the infectious dose) is low, and a number of waterborne disease outbreaks caused by this protozoan have occurred all over the world, and continue to do so. The problem is aggravated by the fact that Cryptosporidium is resistant to commonly used water disinfection practices such as chlorination and by the fact that presently there are no drugs effective in preventing or controlling gastroenteritis caused by Cryptosporidium. 
Giardiasis is the most commonly reported intestinal protozoan infection worldwide. The World Health Organization estimates 200 million people are infected each year. Human infections with Giardia have been reported in all of the major climatic regions, from the tropics to the arctic. Giardia cysts are ubiquitous in surface waters of all qualities. Because Giardia infections are widespread in human and animal populations, contamination of the environment is inevitable and cysts have been detected in even the most pristine of surface waters.
The human related source of Cryptosporidium and Giardia is treated wastewater. Today there is no surveillance system which monitors microbiological discharge to the nature, i.e. lakes and rivers. Treated or untreated wastewater with microbiological load of varying concentration mixes with lake and river water, which is referred to as “natural dilution”.
Another emerging contamination which, together with pathogens, causes an environmental load on water sources are residues of pharmaceutical products, originating as well from the pharmaceutical industry as from human consumption and animal antibiotics. Furthermore, personal care products have also become an environmental issue of today.
These residues cling to micro contaminants, such as bacteria and protozoa, in a flow of water and cause damage to environment; and ultimately affect human beings. Indeed, wastewater containing drug residues lead to contamination of source water, used for production of drinking water. It appears that pharmaceutical/personal care product residues are an emerging environmental problem on a global scale.
As used herein, the term wastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture. One example of wastewater is municipal wastewater.
Improved sensitive surveillance systems with sampling and inactivation of contaminants to ensure the proper application of different water cleanliness are needed to detect these contaminants. Sudden deterioration in water cleanliness due to the presence of pathogens and pharmaceutical residues in treated wastewater and source/lake water is the challenge of today and of tomorrow.
Treatment of wastewater is necessary to reduce the organic loads and suspended solids, to limit environmental pollution and to avoid health risks. The existing treatment methods used in municipal wastewater are physical, chemical and biological process. The physicochemical process involves primary and secondary sedimentation using chemical precipitation, chemical coagulation, and removal of suspended solids and dissolved matter and filtration. The biological treatment mainly involves activated sludge and biomass production.
This is a very complex system and the complete process takes about 24-40 hours involving various steps in wastewater treatment (Tansel, 2008). The term “total organic carbon” generally refers to carbon bound in organic material derived from decaying vegetation, bacterial growth, and metabolic activities of living organisms or chemicals. High organic carbon in water is an indicator that microbiological growth possible.
Pathogens like Cryptosporidium, Giardia, hookworm, amoebas and bacteria and pharmaceutical residues may be present in untreated or insufficiently treated wastewater and if this water reaches the river/lake, the water becomes unfit as a source for drinking water source as there no monitoring system which gives information about the contamination.
New technologies are being developed for wastewater treatment, like MBR (membrane bio reactors), separations of organics by nano technology, ultra and nano filtration, and so on.
The focus in wastewater treatment of today is to remove Nitrogen and Phosphorus and to convert waste to energy. Nanotechnology and MBR membrane bio reactors of different size and capacity have been identified and developed to provide solutions for many of the difficulties associated with water treatment and quality (Theron et al, 2008)
Considering the importance of potable drinking water globally, and keeping in mind concerns regarding the viability of recent practices for meeting the rising water demands, there is a pressing need to develop novel technologies and materials that will tackle the challenges associated with cleanliness of safe drinking water, recycled water and source and lake water that will be used for different purposes. While new water treatment technologies are being developed today, there is a need for a novel cost effective, user-friendly, robust and more efficient polishing system which in one step can remove/inactivate parasites, such as Cryptosporidium and Giardia as well as pharmaceutical residues in the treated flow of water.
Presently, the normal method of detection of microorganisms in water is to collect 500 ml of random water samples in sterile bottles and then take less than a drop of each sample for analysis. In order to determine the presence of any microorganism, the sample may be subjected to incubation on an agar plate followed by counting of colony forming units on the plate. It goes without saying that such methods have several drawbacks. One drawback is the high risk of undetected contamination due to the random character of sampling. Another drawback is the low sensitivity due to the small volume analyzed: only a fraction of a drop is used for analysis and evaluation out of a 500 ml sample.
For parasites, no standard regular analysis is performed due to high cost and complexity in analyzing. Some bigger water treatment plants analyze samples once a month or once a year. The analysis takes several weeks with high cost. Furthermore, more than 100 liters of water is needed to perform a proper analysis.
However, microbiological contamination is prone to occur from time to time in a water distribution system, for many reasons, for example if, for some reason, treatment of water fails or biofilm loosens in a distribution system. Such microbiological contamination may exist for a very short time, e.g. 5 to 60 seconds, or for a longer time, before the water quality returns to normal again. The state of the art random sampling is not suitable to catch this type of microbiological contamination. Contamination of this nature may occur several times a day/week/month and pass through unnoticed but cause more or less severe health problems at the consumer's end.
U.S. Pat. No. 7,891,235 discloses a method for monitoring water quality in a water system. In this system, a water pipe is provided for conveying water therein. A particle sensor is in operative engagement with the water pipe. The particle sensor continuously counts particles in the water of the water pipe. The particle sensor triggers the taking of a water sample only when the particle count reaches a predetermined level.
International application No. WO/2002/017975 discloses a method of assessing the presence of ozone consuming agents on the surface of an object or within an enclosed volume, by providing a fluid containing ozone, bringing the fluid into contact with the object or introducing the fluid into the enclosed volume, measuring the concentration of ozone in the fluid and evaluating the presence of the ozone consuming agents as a function of the measured ozone concentration. In particular the method is applicable as a method of assessing the cleanness, expressed in terms of the essential absence of ozone consuming agents, of a surface or volume.
International application No. WO/2011/061310 discloses a water supply and monitoring system comprising a first water pipe, a particle sensor for sensing particles in the water at a first location in said pipe; a second pipe, in fluid communication with the first pipe by means of a first valve disposed at a second location on the first pipe downstream of the first location; a third pipe, in fluid communication with the first pipe at a location between the first and second locations; a second valve, allowing water conveyed by the first pipe to flow into the third pipe. Also described is a method using said arrangement, comprising determining a content of particles in the water within a particle size interval within the range of from 0.1 to 100 micrometers in the first pipe; triggering closure of the first valve and opening of the second valve when the determined content of particles is higher than a predetermined level, whereby water flowing in the first pipe is diverted from the second pipe into the third pipe.